1. Field of the Invention
This invention is related in general to the field of railroad operation and, in particular, to an integrated system for controlling the interaction among trains and other vehicles on the system""s tracks to ensure safety and efficiency.
2. Description of the Related Art
Railroads are operated throughout the world using tested technology and procedures designed to guarantee passenger safety and to safeguard the integrity of the rail system. The approaches taken by railroad operators to perform various functions have been adopted with substantial uniformity throughout the industry. As a result, railroads tend to operate in conservative fashion and changes are implemented slowly in the art even when technological advances provide and warrant improvements.
For example, train scheduling and dispatching is carried out mostly as a separate function with substantial manual operations. Train schedules are initially laid out by planners in train graphs where the projected travel schedule of each train is shown in a position-versus-time plot. The graphs show the locations within the system (called xe2x80x9csidingsxe2x80x9d in the art) where trains can be switched off the main line for various operational objectives (park, load, unload, reconfigure) and the times when the trains are expected to reach each location. Thus, the graphs also show where and when trains traveling in opposite directions are expected to cross, or trains traveling in the same direction at different speeds are expected to pass one another. FIG. 1 illustrates a typical train graph showing, for example, the progression of two trains (A and B) traveling between locations 25-58 and 47-1, respectively. As shown, trains A and B crossed at location 39 at about 9 am. At the current time of approximately 17 hours (5 pm), highlighted in the train graph by the moving line T, train A has reached and it stopped at location 58, while train B is departing from location 27, where it has been stopped for about two hours, heading toward location 1.
Train graphs are converted into railroad panels to help dispatchers control the flow of train traffic efficiently and safely. Railroad panels consist of schematic representations of the current condition of various yards along the route traveled by each train. FIG. 2 is a portion of such a panel corresponding to the train graph of FIG. 1. Panels are utilized by dispatchers to schedule the use of maneuvering tracks and yards as needed to allow trains to cross or overtake one another at particular locations, or to be reconfigured according to operational objectives and/or constraints. Thus, for example, the dispatcher may have decided that train A should have the right-of-way when trains A and B cross at location 39 because train A is an express train. Similarly, a dispatcher would make decisions regarding priorities for trains due to cross one another in the future, such as trains B and C, or C and D, in FIG. 1. Accordingly, these priorities would be assigned and reflected in the current train graph and corresponding panel and the dispatcher would implement them by taking appropriate action in dealing with the train""s conductor and/or with automated controls.
The position of each train is determined in real time by the use of a conventional positioning system, such as GPS, and is communicated to the dispatcher, so that the progress of each train can be followed and compared to the expected schedule expressed in the relevant train graph and panel. When a schedule delay or change occurs, adjustments are made by the dispatcher by manually rearranging the schedule reflected in the train graph and corresponding panel according to predetermined safety and efficiency constraints. For example, if train A had been running late and it had become apparent that it wins would not be able to reach location 39 in time to exert its right-of-way over train B without causing an undesirable delay, the dispatcher would have modified the train graph to reflect that change and any other modification to the schedule of other trains necessitated by the change, so that the correct information would be available for dispatching. Keeping track of each train""s position with respect to its schedule and assessing the need or desirability for effecting changes in the train graphs and panels on a current basis is obviously taxing and time consuming for planners and dispatchers. In addition, safety constraints warrant a very conservative approach to making any change to the schedules reflected in active train graphs. Therefore, perturbations to planned train schedules are likely to result in delays and sub-optimal corrections that could be avoided if the process were automated and controlled by an online computerized system under the dispatcher""s supervision.
Another area of sub-optimal operation is the use of maneuvering tracks. These are tracks typically present at sidings around the system for switching trains between main tracks (often referred to as xe2x80x9ccirculationxe2x80x9d tracks) and for changing cars between trains. These tracks may be controlled by the railroad""s main control center, or may be isolated from the system and left totally to local control. In practice, when a conductor wishes to leave a circulation track and enter a maneuvering zone to carry out a particular task, a request is made from the central control center for the release of the train to local operation within a given block of the maneuvering zone. If the release is granted, the control center isolates the train from the rest of the system and stops accounting for its operations until it returns, subject to further approval, to the circulation track. Thus, the system as a whole is unaware of the specific action or operation carried out on the maneuvering tracks so long as the train in question remains inside the maneuvering zone, thereby preventing any coordination with the operations conducted on the circulation tracks of the railroad system. For example, if a derailment or similar problem occurs, the control center and the dispatcher remain unaware until notified by a person. This lack of coordination is another source of potential hazards and loss of operational efficiency.
A similar problem exists with circulation tracks that need to be taken out of service temporarily for maintenance work. A track warrant (a permission to travel along a given segment of track) and/or a maintenance-of-way (an exclusive permission to be present on a segment of track to perform maintenance work) may be granted upon request to reach and maintain the pertinent segment of rail. The segment is then isolated from the supervision of the control center until the maintenance work is accomplished. During the time control of the operation in the maintenance area is released, the control center is not able to account for the current status and progress of the work. Thus, this information is not accounted for or available to optimize the overall operation of the rail system.
Another common prior-art practice in railroad operation is the use of so-called hot boxes to monitor the condition of car wheels and axles during transit. A hot box consists of a sensor device capable of detecting the temperature of a body passing within a given detection zone. A hot wheel is indicative of a potential bearing breakdown and wheel seizure that could have disastrous consequences. Thus, hot boxes are placed along tracks to monitor the temperature of the wheels of locomotives and cars of trains as they pass by. When a hot spot is detected, the hot box sends a signal to the central station, which in turn is then able to alert the train conductor to effect whatever action may be appropriate under the circumstances. This alarm configuration requires the immediate awareness and manual intervention of an operator, which is often missing as a result of distractions or other intervening constraints. In addition, when a train""s schedule is altered as a result of a hot-box alarm, the scheduling changes to the train in question and possibly to other trains within the system are necessarily tied to additional manual operations that require scrutiny for safety concerns and therefore time, as described above. Thus, the urgent response and the immediate system adjustments that could be obtained if the alarm information were communicated directly to the train conductor and were acted upon immediately by the control center are not advantageously achieved in practice.
These examples illustrate the sub-optimal operation of railroad systems even when state-of-the-art technology is utilized. Therefore, it is clear that any form of system integration that improved the efficiency of these and other tasks would constitute a welcome advance in the art. This invention is directed at implementing such an integrated system of operation.
The general objective of this invention is an integrated monitoring and control system for a railroad that permits rapid adjustments to operating parameters in reaction to changes in the system, thereby providing the control infrastructure required for optimal safety and efficiency of operation.
Another objective is a system that makes it possible to account for each operating function and for the extent to which that function affects other operations in the system, so that the effects of perturbations may be analyzed and countered in optimal fashion.
Another object is a system that provides real-time feedback information to planners and dispatchers concerning the effect of any particular proposed change to planned schedules and/or operating conditions.
Yet another object is a system that provides real-time scheduling solutions to planners and dispatchers in response to actual changes to planned schedules and/or operating conditions occurring within the system.
Another goal is a system that is suitable for automated implementation with current railroad safety and operation equipment.
A final objective is a system that can be implemented economically according to the above stated criteria.
Therefore, according to these and other objectives, the broad embodiment of the present invention requires linking each locomotive and/or other moving equipment within the territory covered by the railroad to a control center for communicating data and control signals. Using on-board computers, GPS and two-way communication hardware, rolling stock continuously communicate position, vital sign data, and other information for recording in a data base and for integration in a comprehensive computerized control system. The data base includes train schedules and corresponding railroad panels generated and entered into the system by planners for real time display on monitors and use by dispatchers. The current position of each train, as communicated to the control center, is compared to its planned schedule online to provide immediate information to the dispatcher to determine whether a corrective action is necessary. According to one novel and important aspect of the invention, when a train""s deviation from its planned schedule exceeds a predetermined parameter, the system automatically calculates alternative schedules for all trains in the system according to preselected operational constraints as necessary to minimize the effect of the deviation. Thus, the dispatcher is not only alerted of the schedule change, but is also presented with an immediate re-dispatch solution for consideration that accounts for all operational constraints currently in place in the system. If the solution is accepted by the dispatcher, the train graphs and panels in the system are automatically updated to reflect the changes for immediate availability to planners and dispatchers, thereby providing great advantages to the operation in the form of improved efficiency and savings of time and effort.
According to another aspect of the invention, the trains and other moving equipment in the system are equipped with a data processor connected to the system""s communication network for receiving, transmitting and processing data, and also with an interactive color graphic console for displaying in real time the same panel information available to dispatchers at the control center. The interactive function of the system allows each conductor the flexibility of requesting track warrants for particular tasks by specifying the request through the console directly to the automated system without participation of a dispatcher. The control system evaluates the availability of the requests within the operating parameters and safety constraints of the overall system and, if available, it grants it directly without requiring further action on the part of dispatchers. The system then automatically updates the panels displayed throughout to reflect the presence of the active warrant. Similarly, when the warrant terminates or is released by the conductor, the system automatically reflects the termination in all displayed panels for general information and consideration. By enabling the process of granting and releasing warrants without dispatcher participation, this feature of the invention provides a very advantageous improvement over current practice by freeing dispatchers from time-consuming and inefficient tasks.
According to yet another aspect of the invention, the automated integration of all current operating data of the system make it possible to quickly analyze the effect of any change by artificially entering it into the system and requesting a simulated response in the form of a re-dispatch schedule. Since the control system is programmed to provide optimal solutions according to desired optimization criteria and within the current operating constraints of the system, optimal solutions to alternative factual scenarios may be developed in real time for the dispatcher""s consideration and action. This feature provides a heretofore unknown degree of flexibility to the operation of a railroad.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention consists of the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiment and particularly pointed out in the claims. However, such drawings and description disclose but one of the various ways in which the invention may be practiced.